Compression and vacuum-producing machines are used in a variety of commercial and residential applications to provide a compressed stream of fluid or to extract fluid, respectively. In commercial applications, compression machines are used in devices such as de-icing machines and fire trucks to deliver a compressed fluid (i.e., de-icing fluid and water, respectively). In residential applications, compression machines are used in residential applications such as leaf blowers to disperse yard waste (i.e., leaves, grass clippings, etc.) or in inflatable devices such as yard balloons to maintain an inflated state of the balloon. Furthermore, compression machines are also utilized in residential and commercial vehicles to provide a desired boost in engine performance. Vacuum-producing machines are used in commercial and residential appliances such as vacuum cleaners to provide a desired fluid force suitable to collect waste.
A supercharger is a compression machine that increases the induction pressure of an internal combustion engine. The higher induction pressure creates a higher output power of the engine due the increased air pressure received by each combustion chamber of the engine. In addition, the increased pressure helps to increase the engine power by completely releasing combustion gases and allowing more fuel to be delivered to each chamber. In spark-ignition engines, the range of pressure provided by the supercharger is limited to less than 10 psig by pre-ignition conditions created by the fuel octane number. In diesel cycle engines, such a limitation does not exist. However, for either application, the supercharger must produce a requisite pressure and airflow to each chamber to accommodate a complete range of operation of the engine. In other words, the response of the supercharger must be matched with engine requirements.
Most known superchargers are positive-displacement type superchargers, which allow for simple matching of air delivery and engine requirements. However, while adequately meeting the requisite air requirement, conventional superchargers typically suffer from low efficiency. In addition, the general configuration and high inertia of conventional supercharger components practically precludes the possibility of disconnecting the supercharger from the engine by mechanical means. Therefore, conventional superchargers also suffer from the disadvantage of requiring high power from the engine even when an air boost is not needed, thereby resulting in poor vehicle mileage.
Conventional positive-displacement superchargers typically require high-precision component parts and tight tolerances between such parts to avoid air leaks during rotational movement and air compression. Such high-precision, small-tolerance designs typically mandate a heavy construction to avoid distortions of, and contact between, high-velocity rotating parts. In addition, the inherent low adiabatic efficiency of such superchargers increases the temperature of the air delivered, and thus typically requires cooling with air-to-air heat exchangers or with a radiator and water-circulation system, thereby further increasing the weight and complexity of the system. The complexity and overall weight of conventional superchargers results in a generally inefficient machine and, as such, reduce the overall efficiency of the vehicle to which the supercharger may be tied.
In addition to car and light truck applications, superchargers are also used in heavy transportation, high performance, and racecar applications. Such high-performance superchargers are typically centrifugal-type superchargers and include a higher efficiency than a positive-displacement type supercharger. While centrifugal superchargers have an improved efficiency from positive-displacement type superchargers, centrifugal superchargers suffer from the disadvantage of requiring a bulky and large design to function properly. Such large designs are difficult to apply in cars and light trucks that typically have low profile covers for the engine compartment, and thus, are not practical in such applications.
In addition to positive-type displacement and centrifugal superchargers, turbochargers are also used to increase the pressure of an air stream delivered to an engine. Turbochargers utilize hot gas from an engine exhaust to further compress ambient air delivered to the engine. Hot gas from the engine exhaust is passed through a turbine connected to a centrifugal compressor, thereby compressing the ambient air and delivering a compressed air stream to chambers of the engine. Turbochargers are high-precision machines, requiring special materials, components, and lubrication from the engine system. The delay of the response created by the need for higher exhaust conditions to drive the input turbine and the complex regulation needed for the high-temperature exhaust gases often result in application and reliability problems.
While positive-displacement superchargers, centrifugal superchargers, and turbochargers adequately deliver a compressed stream of air to each combustion chamber of an engine, each system suffers from the disadvantage of requiring a complex design and a large space in which to package the system. Therefore, a supercharger that is easily packaged in an engine compartment of a vehicle is desirable in the industry. Furthermore, a supercharger that provides a low weight construction, high efficiency output, avoids water cooling of compressed air, works with a minimum rotational speed, has a low production cost, is easily installed, and has a high reliability is also desirable.